1. Field of the Invention
This invention relates to a lane boundary recognition system for a self-navigating vehicle, and particularly to such a system as is able for the vehicle to self-navigate on an expressway or other such roadway having lane boundaries while simultaneously identifying and discriminating the continuity of the lane boundaries (lane dividing markers and road boundary markers).
2. Description of the Prior Art
Various vehicle self-guidance technologies involving lane boundary recognition have been proposed. For example, in Japanese Laid-open Patent Publication No. Hei 3-158,976 the assignee discloses a method for recognizing road lane boundaries by discriminating broken lines from among straight line components extracted from an image of the road. On the other hand, Japanese Laid-open Patent Publication No. Sho 62-139,011 teaches a method for deriving loci approximating actual lane boundaries from lines obtained by conducting projective transformation and functionally approximating points indicating lane boundaries selected from an image.
These prior art technologies have a problem in that they do not provide information regarding the continuity of the lane boundaries recognized at a given instant with those recognized earlier. When steering control or the like is to be conducted, therefore, it is necessary to discriminate the continuity of the lane boundaries instant by instant. Moreover, where separate blocks are used for steering control and for recognition of lane boundaries through image processing, the discrimination has to be conducted separately in each block. In addition, the prior art technologies require a particularly large volume of computation at the time the vehicle changes lanes because the change in the positional relationship between the vehicle and the lane boundaries caused by the lane change makes it necessary to carry out another discrimination of the continuity of the lane boundaries following the change. A similar situation also arises when a separate block is provided for recognizing obstacles through the use of radar or the like.